In semiconductor light-emitting devices such as light-emitting diodes (LEDs), it is desirable to increase the light emission efficiency (external quantum efficiency). To this end, it is necessary to improve the internal quantum efficiency and light extraction efficiency.
For instance, T. Fujii, Y. Gao, R. Sharma, E, L. Hu, S. P. DenBaars, and S. Nakamura, Applied Physics Letters vol. 84 No. 6, pp. 855-857 (2004) proposes a configuration for improving the light extraction efficiency. In this configuration, the n-type GaN layer is provided with a surface asperity. However, despite this technique, there is room for improvement in the efficiency of semiconductor light-emitting devices.